POWER LOSS (mW) LTC3787 PolyPhase Synchronous Boost Controller FEATURES DESCRIPTION n 2-Phase Operation Reduces Required Input and The LTC 3787 is a high performance PolyPhase single Output Capacitance and Power Supply Induced Noise output synchronous boost converter controller that drives n Synchronous Operation for Highest Efficiency and two N-channel power MOSFET stages out-of-phase. Reduced Heat Dissipation Multiphase operation reduces input and output capacitor n Wide V Range: 4.5V to 38V (40V Abs Max) and requirements and allows the use of smaller inductors than IN Operates Down to 2.5V After Start-Up the single-phase equivalent. Synchronous rectification in- n Output Voltage Up to 60V creases efficiency, reduces power losses and eases thermal n 1% 1.200V Reference Voltage requirements, enabling high power boost applications. n R or Inductor DCR Current Sensing SENSE A 4.5V to 38V input supply range encompasses a wide n 100% Duty Cycle Capability for Synchronous MOSFET range of system architectures and battery chemistries. n Low Quiescent Current: 135A When biased from the output of the boost converter or n Phase-Lockable Frequency (75kHz to 850kHz) another auxiliary supply, the LTC3787 can operate from n Programmable Fixed Frequency (50kHz to 900kHz) an input supply as low as 2.5V after start-up. The operat- n Power Good Output Voltage Monitor ing frequency can be set for a 50kHz to 900kHz range or n Low Shutdown Current, I < 8A Q synchronized to an external clock using the internal PLL. n Internal LDO Powers Gate Drive from VBIAS or EXTV CC PolyPhase operation allows the LTC3787 to be configured n Thermally Enhanced Low Profile 28-Pin 4mm 5mm for 2-, 3-, 4-, 6- and 12-phase operation. QFN Package and Narrow SSOP Package The SS pin ramps the output voltage during start-up. The PLLIN/MODE pin selects Burst Mode operation, pulse- APPLICATIONS skipping mode or forced continuous mode at light loads. n Industrial L, LT, LTC, LTM, Linear Technology, the Linear logo, Burst Mode, OPTI-LOOP and PolyPhase n and ThinSOT are trademarks of Linear Technology Automotive are registered trademarks and No R SENSE Corporation. All other trademarks are the property of their respective owners. Protected by n Medical U. S. Patents, including 5408150, 5481178, 5705919, 5929620, 6144194, 6177787, 6580258. n Military TYPICAL APPLICATION Efficiency and Power Loss 12V to 24V/10A 2-Phase Synchronous Boost Converter vs Output Current V 4.5V TO 24V START-UP VOLTAGE IN V 100 10000 IN OPERATES THROUGH TRANSIENTS DOWN TO 2.5V 90 80 1000 4.7F 4.7F 47F 4m 4m 70 TG1 VBIAS INTV TG2 CC 60 100 3.3H 3.3H BOOST1 50 BOOST2 0.1F 0.1F V OUT 40 10 SW1 SW2 24V AT 10A LTC3787 BG1 30 BG2 + SENSE1 V = 12V IN 20 1 + V = 24V 232k SENSE1 OUT SENSE2 10 Burst Mode OPERATION VFB FIGURE 10 CIRCUIT FREQ SENSE2 0 0.1 PGND PLLIN/MODE 0.00001 0.0001 0.001 0.01 0.1 1 10 ITH SS SGND OUTPUT CURRENT (A) 3787 TA01b 15nF 220F 12.1k BURST EFFICIENCY 100pF 8.66k BURST LOSS 0.1F 3787 TA01a 3787fc 1 EFFICIENCY (%)LTC3787 (Notes 1, 3) ABSOLUTE MAXIMUM RATINGS VBIAS ........................................................ 0.3V to 40V EXTV ........................................................ 0.3V to 6V CC + + BOOST1 and BOOST2 ................................ 0.3V to 76V SENSE1 , SENSE1 , SENSE2 , SENSE2 ... 0.3V to 40V + + SW1 and SW2 ............................................ 0.3V to 70V (SENSE1 - SENSE1 ), (SENSE2 - SENSE2 ) ...0.3V to 0.3V RUN ............................................................. 0.3V to 8V ILIM, SS, ITH, FREQ, PHASMD, VFB .....0.3V to INTV CC Maximum Current Sourced into Pin Operating Junction Temperature From Source >8V ..............................................100A Range (Note 2) ........................................55C to 150C PGOOD, PLLIN/MODE ................................. 0.3V to 6V Storage Temperature Range .................. 65C to 150C INTV , (BOOST1 - SW1), (BOOST2 - SW2) ...0.3V to 6V CC PIN CONFIGURATION TOP VIEW TOP VIEW ILIM 1 28 PGOOD + SENSE1 2 27 SW1 28 27 26 25 24 23 SENSE1 3 26 TG1 FREQ 1 22 BOOST1 FREQ 4 25 BOOST1 2 21 BG1 PHASMD PHASMD 5 24 BG1 3 20 VBIAS CLKOUT CLKOUT 6 23 VBIAS 4 19 PGND PLLIN/MODE 29 PLLIN/MODE 7 22 PGND GND 5 18 EXTV SGND CC SGND 8 21 EXTV CC 6 17 INTV RUN CC RUN 9 20 INTV CC 7 16 BG2 SS SS 10 19 BG2 8 15 BOOST2 SENSE2 SENSE2 11 18 BOOST2 9 10 11 12 13 14 + SENSE2 12 17 TG2 VFB 13 16 SW2 ITH 14 15 NC UFD PACKAGE 28-LEAD (4mm s 5mm) PLASTIC QFN GN PACKAGE 28-LEAD PLASTIC SSOP T = 125C, = 43C/W JMAX JA EXPOSED PAD (PIN 29) IS GND, MUST BE CONNECTED TO GND T = 125C, = 90C/W JMAX JA ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC3787EUFD PBF LTC3787EUFD TRPBF 3787 28-Lead (4mm 5mm) Plastic QFN 40C to 125C LTC3787IUFD PBF LTC3787IUFD TRPBF 3787 28-Lead (4mm 5mm) Plastic QFN 40C to 125C LTC3787HUFD PBF LTC3787HUFD TRPBF 3787 28-Lead (4mm 5mm) Plastic QFN 40C to 150C LTC3787MPUFD PBF LTC3787MPUFD TRPBF 3787 55C to 150C 28-Lead (4mm 5mm) Plastic QFN LTC3787EGN PBF LTC3787EGN TRPBF LTC3787GN 28-Lead Plastic SSOP 40C to 125C LTC3787IGN PBF LTC3787IGN TRPBF LTC3787GN 28-Lead Plastic SSOP 40C to 125C LTC3787HGN PBF LTC3787HGN TRPBF LTC3787GN 28-Lead Plastic SSOP 40C to 150C LTC3787MPGN PBF LTC3787MPGN TRPBF LTC3787GN 28-Lead Plastic SSOP 55C to 150C Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container. 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